Guaranteed Sterilized via Gamma Irradiation Process. Precision & Convenience. Designed to determine bio-burden counts on working surfaces. Grid consists of 16 (10x10 mm) squares marked numerically in one direction and alphabetically in the other. Media well permits dish and media to be inverted and placed in contact with working surface. Unique outer ring construction prevents contamination from fingers touching the media. Suitable for all automated filling equipment.